Recently, in the field of silver halide photographic light-sensitive materials, in particular, used for photographing, those having high sensitivity as typically illustrated by ISO 1,000 films, etc. or those having high image quality and high resolving power suitable for use in small format cameras as typically illustrated by 110 sized cameras or disc cameras have been desired.
For the purpose of increasing the sensitivity, investigations have been made on various techniques including, e.g., large size silver halide grains, couplers with high activities, accelerated development, etc. However, the increase in sensitivity based on large size silver halide grains seems to be reaching its limit, as reported by G. C. Farnell and J. B. Chanter in Journal of Photographic Science, Vol. 9, page 75 (1961). Accordingly, this technique is not expected to make much contribution in the future. In addition, the use of large size silver halide grains is accompanied by various disadvantages, such as deterioration in graininess, increase in thickness of the emulsion layer, and degradation of preservability. Further, the increase in sensitivity by the use of highly active couplers or the accelerated development is disadvantageous since these techniques not only are accompanied by remarkable deterioration in graininess but also have not made much contribution to the sensitivity.
On the other hand, in order to improve the graininess of color images there have hitherto been attempted to increase the number of silver halide grains and to make due clouds formed by color development indefinite as describes in T. H. James, Theory of the Photographic Process, 4th Ed., pages 620-621. However, the attempt at increasing the number of silver halide grains while maintaining a high photographic sensitivity requires an increase in the amount of coated silver and thus causes a reduction in resolving powder. Thus this attempt is disadvantageous in view of cost and photographic properties.
Further, the attempt at improving graininess by diffusion of dyes based on the description in the above-described literature has been disclosed in British Pat. No. 2,080,640A.
It has been surprisingly found that when large size silver halide grains which are intended to obtain high sensitivity are employed in combination with a non-diffusible coupler which forms a properly smearing diffusible dye upon reaction with the oxidation product of a color developing agent (hereinafter, the non-diffusible coupler is simply referred to as a dye diffusible type coupler) in the same layer, not only the graininess is improved but also the sensitivity is further increased compared with a combination of the large size silver halide grains and a conventional coupler providing a non-diffusible dye, although only graininess is improved when a dye diffusible type coupler is employed in combination with silver halide grains having a grain size conventionally used in the same layer, compared with a case wherein a conventional coupler providing a non-diffusible dye is employed therewith. This fact is unexpected from usual knowledge.